Contact LensesContact Lenses

Overview of basics and Overview of basics and considerations for fittingconsiderations for fitting

OutlineOutline

SolutionsSolutions Soft LensesSoft Lenses

– When to useWhen to use RGP LensesRGP Lenses

– When to useWhen to use Contacts and the Contacts and the

presbyopepresbyope OtherOther

Contact lens solutionsContact lens solutions

Soft lens solutionsSoft lens solutions

Rigid gas permeable lens Rigid gas permeable lens solutionssolutions

Compliance always an issue

CL history is keyCL history is key

How many yearsHow many years How many days/weekHow many days/week What brandWhat brand Do you use EWDo you use EW Do you swimDo you swim How do you cleanHow do you clean Are you having any problems?Are you having any problems?

Types of soft lensesTypes of soft lenses

SphericalToric

truncatedprism ballastthin ballast

AphakicExtended wearBifocalBandage lensesHigh dK/lColored/cosmeticColored/prosthetic

Different polymersDifferent polymers– Ionic high waterIonic high water– Ionic low waterIonic low water– Non-ionic high waterNon-ionic high water– Non-ionic low waterNon-ionic low water

Newer siliconeNewer silicone

Types of soft lensesTypes of soft lenses

Conventional (sphere/toric)Conventional (sphere/toric)– Keep for a yearKeep for a year– BifocalsBifocals– Higher powers/cylHigher powers/cyl

Disposable (sphere/toric/bifocals)Disposable (sphere/toric/bifocals)– QuarterlyQuarterly– MonthlyMonthly– Weekly or Two weekWeekly or Two week– DailyDaily

Why/Why not soft Why/Why not soft lenses?lenses? AdvantagesAdvantages

– ComfortableComfortable– AvailableAvailable– Easy to fitEasy to fit– Good for social Good for social

useuse– Better for internal Better for internal

cylcyl

DisadvantagesDisadvantages– More risk of infectionMore risk of infection– Dry outDry out– Prone to rotation Prone to rotation

(toric)(toric)– Get dirty quicklyGet dirty quickly– NoncomplianceNoncompliance– Poor OxygenationPoor Oxygenation– GPCGPC

Fitting the spherical ptFitting the spherical pt

Use soft spheres if cyl is < .75D Use soft spheres if cyl is < .75D

Get good MR, switch to minus cyl formGet good MR, switch to minus cyl form

Find the SEFind the SE

VertexVertex

Keratometry: is K flat or steepKeratometry: is K flat or steep

Select materialSelect material

Select BC/diameterSelect BC/diameter

Fitting the Soft SphereFitting the Soft Sphere

Place lens on eye, best to wait 15 to 20 min Place lens on eye, best to wait 15 to 20 min to assess fitto assess fit

VA (D) and sometimes VA (N)VA (D) and sometimes VA (N) Over refract to check your powerOver refract to check your power Assess fit/movementAssess fit/movement

– loose (flat fit) loose (flat fit) – Tight (steep fit)Tight (steep fit)– CentrationCentration– Coverage (at least .5mm all around)Coverage (at least .5mm all around)– Stability (.5mm in primary, .75mm in upward)Stability (.5mm in primary, .75mm in upward)– Is pt comfortable?Is pt comfortable?

Soft CL problem- Soft CL problem- spheresphere Patient’s Rx is -5.00 -1.00 x 090 Patient’s Rx is -5.00 -1.00 x 090

all cyl is cornealall cyl is corneal K’s 44.50/45.50K’s 44.50/45.50

Patient cannot afford toric lenses- Patient cannot afford toric lenses- what do you prescribe?what do you prescribe?

Fitting the astigmat Fitting the astigmat with soft lenseswith soft lenses IndicationsIndications

– Cyl Cyl >.75D>.75D, but if , but if too large may not too large may not be successful d/t be successful d/t rotation effects rotation effects (blinking (blinking dynamics)dynamics)

– K plus lenticular K plus lenticular cyl, esp ATR cyl, esp ATR

– NOTNOT good for pts good for pts with irregular with irregular corneascorneas

Becherer Twist TestBecherer Twist Test20deg rot OK=90% 20deg rot OK=90% 15 deg rot OK=90% 15 deg rot OK=90%

with 2 lenseswith 2 lenses10 deg rot OK=70% 10 deg rot OK=70%

with 3 lenseswith 3 lenses5 deg rot OK=pt 5 deg rot OK=pt

must accept must accept variable vision with variable vision with soft toricsoft toric

Fitting the astigmat Fitting the astigmat with soft toric lenseswith soft toric lenses Methods for lens stabilizationMethods for lens stabilization

– Prism ballast with prism or Prism ballast with prism or truncationtruncation

– Thin zones u/lThin zones u/l

Fitting methodFitting method

Best to use trial lenses!Best to use trial lenses!

Select BC firstSelect BC first

Then axis (+/- 20)Then axis (+/- 20)

Cyl power (lower better)Cyl power (lower better)

Sph power (least minus)Sph power (least minus)

Wait 15-20 min.Wait 15-20 min.

Fitting considerations Fitting considerations for the astigmatfor the astigmat Assess fit/movementAssess fit/movement

– loose loose (flat fit) - will rotate(flat fit) - will rotate– Tight Tight (steep fit)- reduce rotation but harmful(steep fit)- reduce rotation but harmful– CentrationCentration- same as sphere- same as sphere– CoverageCoverage (at least .5mm all around but (at least .5mm all around but

sometimes bigger is more stable)sometimes bigger is more stable)– StabilityStability (.5mm in primary, .75mm in (.5mm in primary, .75mm in

upward)upward)– Rotation in primary gaze should not exceed Rotation in primary gaze should not exceed

15 degrees15 degrees

Fitting the astigmat Fitting the astigmat with soft lenseswith soft lenses To determine final cl powerTo determine final cl power

– Sphero cyl OR then place trial cl Sphero cyl OR then place trial cl power and OR power in lensometer.power and OR power in lensometer.

– LARSLARS (each clock hour is 30 degrees (each clock hour is 30 degrees If lens base rotates to your Left X If lens base rotates to your Left X

degrees, Add X to spectacle cyldegrees, Add X to spectacle cyl If lens base rotates to your right X If lens base rotates to your right X

degrees, subtract X from spectacle cyldegrees, subtract X from spectacle cyl

SummarySummary

Even when optimally fitted, vision Even when optimally fitted, vision will be worse than with glasseswill be worse than with glasses

Consider first lens will be a trial, Consider first lens will be a trial, rarely one lens is sufficientrarely one lens is sufficient

Failure rate is about 10%Failure rate is about 10%

Toric Soft CL problemToric Soft CL problem

Patient’s Rx: -6.50+2.00x045Patient’s Rx: -6.50+2.00x045 K readings: K readings: 45.00/46.00@13545.00/46.00@135

-What power CL?-What power CL? - What bc? (choice is 8.7 or 8.2)- What bc? (choice is 8.7 or 8.2) - Say CL OR is -1.00 – 0.50 x 040 what do - Say CL OR is -1.00 – 0.50 x 040 what do you do? you do?

-What if OR is -1.00 -0.75 x 090?-What if OR is -1.00 -0.75 x 090? - What if lens is rotating 20 degrees nasal?- What if lens is rotating 20 degrees nasal?

OutlineOutline

Optics of Optics of contactscontacts

Soft LensesSoft Lenses RGP LensesRGP Lenses Bifocal LensesBifocal Lenses Fitting Fitting

proceduresprocedures

Types of RGP’sTypes of RGP’s

SphericalSpherical AsphericAspheric ToricToric

– Back surface toricBack surface toric– Front surface toricFront surface toric– BitoricBitoric

SPESPE CPECPE

BifocalBifocal– AsphericAspheric– SegmentedSegmented– Aspheric and Aspheric and

segmentedsegmented

AphakicAphakic Reverse geometryReverse geometry IntralimbalIntralimbal Mini-scleralMini-scleral ScleralScleral

Anatomy of RGP CLAnatomy of RGP CL

Bc/power/diameter/optic zone/peripheral curves/ CT/material/color

RGP why/why not?RGP why/why not?

AdvantagesAdvantages– More OxygenMore Oxygen– CheaperCheaper– Less surface areaLess surface area– Better for dry eyeBetter for dry eye– Masks corneal cylMasks corneal cyl– ComplianceCompliance– Rare sleepingRare sleeping– Rare infectionRare infection– Superior opticsSuperior optics– K neo recedesK neo recedes– Less abuseLess abuse

DisadvantagesDisadvantages– AdaptationAdaptation– Chair timeChair time– MisconceptionMisconception– Learning to fitLearning to fit

Fitting PhilosophiesFitting Philosophies

Lid AttachmentLid Attachment– Fit is under the lidFit is under the lid– Moves with blinkMoves with blink– More comfortableMore comfortable– Less GPCLess GPC

InterpalpebralInterpalpebral– Wide eyesWide eyes– Must have good recoveryMust have good recovery– ToricsTorics

RGP spherical fitsRGP spherical fits

High myopiaHigh myopia FT contact lens wearFT contact lens wear Corneal cylCorneal cyl up to 2.50D (if more, up to 2.50D (if more,

then the lens doesn’t fit well)then the lens doesn’t fit well) Not great for lenticular cylNot great for lenticular cyl

RGP sphere fit methodRGP sphere fit method

RefractionRefraction- minus power form, SE, - minus power form, SE, vertex dist corrected as for soft lensesvertex dist corrected as for soft lenses

Keratometry Keratometry VERY VERY IMPORTANT!!!!!!!!!!!!!!!IMPORTANT!!!!!!!!!!!!!!!

Select design-Select design- try on if possible try on if possible– Std v asphericStd v aspheric– Material (high dK means flexure, may need Material (high dK means flexure, may need

to increase CT .03mm)to increase CT .03mm)– Consider pupil size for OZConsider pupil size for OZ– Thin flex (intentional flexure)Thin flex (intentional flexure)

– 1D k cyl WTR or ATR residual cyl1D k cyl WTR or ATR residual cyl

Fluorescein PatternsFluorescein Patterns

     Next  >>More Fluorescein Patterns:     1     2     3Making Lens Design ChangesFitting Pearls

     Next  >>More Fluorescein Patterns:     1     2     3Making Lens Design ChangesFitting Pearls

                                                                                                                                                          

                                                                                                                                                          

Alignment pattern

Even pattern centrally with slightly

greater clearance peripherally

Spherical BC on 3D WTR

astigmatic cornea

Horizontal bearing and excessive

vertical pooling is observed

                                                                                                                                                          

                                                                                                                                                          

Alignment pattern

Even pattern centrally with slightly

greater clearance peripherally

Spherical BC on 3D WTR

astigmatic cornea

Horizontal bearing and excessive

vertical pooling is observed

                                                                                                                                                          

                                                                                                                                                          

Alignment pattern

Even pattern centrally with slightly

greater clearance peripherally

Spherical BC on 3D WTR

astigmatic cornea

Horizontal bearing and excessive

vertical pooling is observed

Observe apical clearance andinsufficient peripheral clearance

On K 95/84

More alignmet with greaterPeripheral clearance

On K 95/76

Good edge, bit narrow

Bicurve design with a10.0mm PCR; .5mm wide

An increase in edge clearancecan be observed

Bicurve design with a10.0mm PCR; 1.0mm wide

Insufficient edge clearancecan be observed

Bicurve design with a9.0mm PCR; .8mm wide

Observe greater clearance

12mm PCR, .8mm wide

Lacrimal LensLacrimal Lens

A rgp interacts with the A rgp interacts with the tearstears This is why keratometry becomes This is why keratometry becomes

importantimportant– As long as rgp maintains it’s bc, the As long as rgp maintains it’s bc, the

interface between the lens and the interface between the lens and the tears is spherical (elimiates tears is spherical (elimiates astigmatism)astigmatism) Rgp does not affect internal Rgp does not affect internal

astigmatism!!astigmatism!!

Lacrimal LensLacrimal Lens

Steeper contact creates a + power LL

Flatter contact creates a – power LL

For every BC change, and equal and opposite change of power is needed .05mm=0.25D

Lacrimal Lens ProblemLacrimal Lens Problem

CL parameters:CL parameters:

7.50/-6.00/957.50/-6.00/95

Need to steepen Need to steepen BC .5D what is new BC .5D what is new power?power?

Need to flatten BC Need to flatten BC by .75D what is new by .75D what is new power?power?

Flexure RGPsFlexure RGPs

Flex to the steepest meridianFlex to the steepest meridian– Wtr cornea, lens steepens in the Wtr cornea, lens steepens in the

vertical and slightly flattens in the vertical and slightly flattens in the horizontal.horizontal.

– Measured as toricity with over-K’sMeasured as toricity with over-K’s– Calculated effect is to lessen the Calculated effect is to lessen the

minus power of the LL in the minus power of the LL in the steepest meridiansteepest meridian

RGP ProblemRGP Problem

Rx:Rx: -8.50DS -8.50DS K: K:

44.50/46.00@7844.50/46.00@78 What power?What power? What BC?What BC?

How to manipulate fitHow to manipulate fit

To center the lensTo center the lens

steepen bcsteepen bc

decrease decrease diameterdiameter

To make lens LA fitTo make lens LA fit

flatter bcflatter bc

increased increased diameterdiameter

Pay attention to Pay attention to the periphery the periphery (tear meniscus)(tear meniscus)– Too tightToo tight– Too looseToo loose

Insufficient edge clearancecan be observed

Bicurve design with a9.0mm PCR; .8mm wide

Observe greater clearance

12mm PCR, .8mm wide

Astigmatism and RGPsAstigmatism and RGPs

Back surface toricBack surface toric Toricity on back, sphere on frontToricity on back, sphere on front

use with lots of k cyl (2D or more) will use with lots of k cyl (2D or more) will provide a better fit to produce alignmentprovide a better fit to produce alignment

LL is altered, filled with plastic LL is altered, filled with plastic

Higher (n) so greater refractive effectHigher (n) so greater refractive effect

Back surface toricBack surface toric

Determine BC first (need accurate Determine BC first (need accurate K’s)K’s)

.25D flatter than flat K.25D flatter than flat K Steep K determined by making toricity ¾ of K Steep K determined by making toricity ¾ of K

cyl (flat BC + ¾ change in BC)cyl (flat BC + ¾ change in BC) Power is toric and specified for each meridianPower is toric and specified for each meridian LL in flat meridian, leave power for steep LL in flat meridian, leave power for steep

meridian unspecifiedmeridian unspecified Make toric peripheral curves to create a Make toric peripheral curves to create a

round OZround OZ

Back surface toricBack surface toric

Assess fit- should Assess fit- should look alignedlook aligned

Dot flat meridian Dot flat meridian to assess rotation- to assess rotation- should align with should align with flat meridian and flat meridian and not rotate.not rotate.

Perform spherocyl Perform spherocyl OROR

BitoricBitoric

SPE (spherical power effect) bitoric has SPE (spherical power effect) bitoric has both front and back toric surfaces.both front and back toric surfaces.

Fits like a toric, but has the optics of a Fits like a toric, but has the optics of a sphere when combined with the LLsphere when combined with the LL

Indications:Indications: K cyl >2DK cyl >2D Refractive astig w/in .75D of K cylRefractive astig w/in .75D of K cyl Good vision with sphere but Good vision with sphere but poor fitpoor fit Lens can rotate around w/o affecting Lens can rotate around w/o affecting

visionvision

BitoricBitoric

CPE (cylinder power effect)CPE (cylinder power effect) Use for eyes with significant K (1.5D) Use for eyes with significant K (1.5D)

andand internal cyl (>.75D). internal cyl (>.75D). – Back surface corrects the K cyl, the front Back surface corrects the K cyl, the front

surface corrects the internal cyl.surface corrects the internal cyl. The toricity of BC and power are The toricity of BC and power are

different, so must be stabilizeddifferent, so must be stabilized– Lens can’t rotateLens can’t rotate– Prism.Prism.

Front surface toricFront surface toric

Signficant internal astigmatism Signficant internal astigmatism with a relatively spherical cornea with a relatively spherical cornea (less than 1.5D)(less than 1.5D)

Fits like spherical lens on back, Fits like spherical lens on back, but toric surface on the front. but toric surface on the front. Front power is the cyl that is left Front power is the cyl that is left over on the ORover on the OR

Has to be stabilized with prismHas to be stabilized with prism

RGP ProblemRGP Problem

Rx: Rx:

-3.00 + 6.00 X 090-3.00 + 6.00 X 090 K:K:

42.50/47.75@1842.50/47.75@1800

What bc (spe)?What bc (spe)? What power?What power?

Therapeutic fitsTherapeutic fits

Irregular corneasIrregular corneas– KCKC– PellucidPellucid– K lacsK lacs– Refractive induced keratoectasiaRefractive induced keratoectasia– Post graftsPost grafts

Therapeutic RGP fitsTherapeutic RGP fits

Use topography and SLE to assess Use topography and SLE to assess KK– Where are scarsWhere are scars– What is steep/flat etc.What is steep/flat etc.

Goal is to fill in irregular part with Goal is to fill in irregular part with tearstears

Pick steepest K as starting pointPick steepest K as starting point Just fit the lens and then OR to get Just fit the lens and then OR to get

powerpower

Therapeutic fitsTherapeutic fits

Irregular corneas may require Irregular corneas may require larger diameter lenses with larger diameter lenses with multiple peripheral curvesmultiple peripheral curves– IntralimbalIntralimbal– MiniscleralMiniscleral– ScleralScleral

Therapeutic fitsTherapeutic fits

Pt expectations criticalPt expectations critical– Vision improves BUTVision improves BUT– Lenses take time to get used toLenses take time to get used to– Careful f/u is necessaryCareful f/u is necessary– Lenses are usually NOT covered by Lenses are usually NOT covered by

insuranceinsurance

AphakiaAphakia

Soft lensesSoft lenses Rigid lensesRigid lenses

CLS and the presbyopeCLS and the presbyope

Monovision is the Monovision is the easiest/cheapesteasiest/cheapest– Best for those under 40Best for those under 40– Without stereo vision needsWithout stereo vision needs– Not too pickyNot too picky– OK with part time glassesOK with part time glasses

Monovision fitMonovision fit

48 yo female, OD dominant48 yo female, OD dominant RX: -5.00 +1.00 x 180 ADD RX: -5.00 +1.00 x 180 ADD

+1.50+1.50 -4.25 DS ADD +1.50-4.25 DS ADD +1.50

What would you prescribe?What would you prescribe? Same for lasik/refractive ptsSame for lasik/refractive pts

Bifocals – soft lensesBifocals – soft lenses

D

N

N

D

D

N

I

Simultaneous vision

aspheric

Bifocal RGPBifocal RGP

aspheric

n

d aspheric

Bifocal RGP fittingBifocal RGP fitting

Many different Many different brandsbrands

ProprietaryProprietary Fitting is specific Fitting is specific

to brand/ typeto brand/ type Many potential Many potential

changeschanges

Set realistic Set realistic expectationsexpectations

Acknowlegde Acknowlegde time investmenttime investment

$350 fit/$300 $350 fit/$300 lenses- self paylenses- self pay

CRTCRTUse of high dK,RGP cl Use of high dK,RGP cl

at nighttimeat nighttime

Reverse geometry Reverse geometry designdesign

Advances in Advances in topographytopography

Nothing is worn during Nothing is worn during the daythe day

Moulds the cornea Moulds the cornea much like braces much like braces retainerretainer

rgp

crt

CRTCRT

THE BASICSTHE BASICS

Details of previous cl wearDetails of previous cl wear What are the problems?What are the problems? When/how do you wear them?When/how do you wear them? Careful refraction (vertex over +/-4D)Careful refraction (vertex over +/-4D) Keratometry or topographyKeratometry or topography Examination of the cornea, lids, lashesExamination of the cornea, lids, lashes Dryness…..? MUST FIX.Dryness…..? MUST FIX. Pupil size (dim/light)Pupil size (dim/light) Palpebral Apeture/ characteristics –tight/loose Palpebral Apeture/ characteristics –tight/loose

etc.etc. Iris DiamterIris Diamter

CL fittingCL fitting

Fit the lensFit the lens Follow up in 2-4 weeksFollow up in 2-4 weeks Tell pts which solutions to useTell pts which solutions to use Refit if neededRefit if needed

The BasicsThe Basics

Technicians are key to Technicians are key to profitabilityprofitability

Insertion/removal trainingInsertion/removal training Lens hygiene teachingLens hygiene teaching Patient follow up- phone callsPatient follow up- phone calls

FOLLOW UP IS IMPERATIVE…FOLLOW UP IS IMPERATIVE…